Electrochemically splitting water for hydrogen evolution has attracted a lot attention and developed into a promising approach to produce hydrogen energy. Searching for high-activity and economical electrocatalysts to replace Pt-based catalysts remains a great challenge. In this paper, we reported a concise and effective strategy to fabricate the novel MoWS2 composite for use as the electrocatalyst through a hydrothermal method for the first time. The final obtained MoWS2 composite demonstrated a well-defined hierarchical structure and established that its densely stacked nanopetals act as the active sites in the corresponding hydrogen evolution reaction (HER) processes. Experimental results show that the composites can deliver a clearly promoted HER activity and are superior to the pure structure. In order to give a more in-depth explanation, we also performed a first-principles calculation to further survey the electronic properties, compound form, and HER mechanism of different structures. The charge distribution of MoWS2 composite indicates that electrons can directionally transfer from WS2 to the neighboring MoS2 and form an "electron-rich" configuration, which is beneficial to increase the HER rate and promote the overall performance. This thorough research will not only provide new thought to the analyses and elucidation of the inner mechanism of the HER process for this kind of two-dimensional composite but also guide further work on the basis of experimental and calculation results.
Keywords: MoS2; electrocatalysis; electronic structures; heterojunction; hydrogen.